1. Field of the Invention
The present invention provides a multiple flow and direction control valve and more particularly, but not by way of limitation, to stackable valve body members to provide multiple hydraulic flow selection and directional control to operate various hydraulic apparatus.
2. History of the Prior Art
Fluid power engineers are constantly confronted with the need for being able to drive fluid motors and hydraulic rams, jacks and the like at different rates of speed and to simultaneously be able to control the direction of operation of such equipment.
For instance a typical hydraulic motor is a positive displacement motor or also known as a constant displacement motor, the speed of which can be varied only by increasing the fluid flow rate through the motor. Such hydraulic motors are also operable in either direction by alternately applying fluid flow through the motor in either direction. This is also true of hydraulic rams and jacks which are double acting whereby fluid can be applied under pressure to either side of the hydraulic piston within the ram or jack.
The variable speed of motors, rams, jacks and the like, is typically accomplished by either increasing the fluid pressure causing a higher flow rate through the equipment or by connecting several pumps in parallel through a series of valves to adjust the flow rate through the hydraulic equipment.
The varying of pressure is often impractical since the fluid sources available are also used to operate ancillary equipment such as hydraulic jacks, rams or the like, which often must operate on a lower pressure.
The use of a plurality of parallel hydraulic power sources requires a large number of valves to be connected in parallel and in series in order to put one or more of the hydraulic pumps on the line in connection with the motor or hydraulic equipment to be driven. This solution is costly and increases the likelihood of system failure due to the introduction of many separate valve components.
Further, as stated, it is often desirable to control the direction of flow through the hydraulic equipment which usually requires a separate directional control valve for each unit being operated.
Often the operator of such systems is faced with a large number of valves that must be sequentially operated which gives rise to mistakes being made in operating the right valve at the right time. Such units are further undesirable in that it is extremely complicated to train new operators since each such valve arrangement is usually different for different pieces of equipment.
Another problem associated with the use of several separate valves in series and parallel is that of hydraulic shock encountered by not being able to "feather" or gradually bring in a new volume rate by simultaneously opening and closing several valves.